Quantum critical metamagnetism of Sr3Ru2O7 under hydrostatic pressure

W. WU; A. MCCOLLAM; S. A. GRIGERA; R. S. PERRY; A. P. MACKENZIE; S. R. JULIAN

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Año: 2011 vol. 83 p. 4510601 - 4510607

1098-0121

Using ac susceptibility, we have determined the pressure dependence of the metamagnetic critical endpoint temperature T ∗ for a field applied in the ab plane in the itinerant metamagnet Sr3Ru2O7. We find that T ∗ falls monotonically to zero as pressure increases, producing a quantum critical endpoint (QCEP) at Pc ∼ 13.6 ± 0.2 kbar. New features are observed near the QCEP—the slope of T ∗ versus pressure changes at ∼12.8 kbar, and weak subsidiary maxima appear on either side of the main susceptibility peak at pressures near Pc—indicating that some new physics comes into play near the QCEP. Clear signatures of a nematic phase, however, that were seen in field-angle tuning of T ∗ are not observed. As T ∗ is suppressed by pressure, the metamagnetic peak in the susceptibility remains sharp as a function of an applied magnetic field. As a function of temperature, however, the peak becomes broad with only a very weak maximum, suggesting that, near the QCEP, the uniform magnetization density is not the order parameter for the metamagnetic transition.